In order to facilitate printing of images in a printing device, an image having continuous tones (also referred to as a “continuous tone image” or a “contone image”) is often converted into an image having halftones. A pixel of the contone image may be represented, for each color plane, by a plurality of bits, e.g., 8 bits, 10 bits, or the like. Subsequent to converting the contone image into a corresponding halftone image, each pixel of the halftone image may be represented, for each color plane, by one or more bits, e.g., 1 bit, 2 bits, or the like. A halftone image may be generated from a contone image using, for example, one of error diffusion halftoning process, multi-bit halftoning process, threshold halftoning process, or the like.
As discussed, in a halftone image, each pixel is represented by, for example, one or more bits of data. For example, a one bit data associated with a pixel of a halftone image represents whether, during a printing process, a dot is to be placed corresponding to the pixel. A two bit data associated with a pixel of a halftone image represents, during a printing process, whether a dot is to be placed corresponding to the pixel, and a level of the dot (e.g., a size, a tone, an optical density with which the corresponding pixel of the halftone image is to be printed while printing the halftone image, or the like).
When a laser printer prints a halftone image, dots of low optical density (e.g., small sized dots) tend not to form very well. For example, a process of placing charge on a developer roller of an Electrophotographic engine (which is commonly found in laser printers) and causing toner to jump to the developer roller (e.g., prior to printing the image) works relatively better with dots of medium or high optical density (e.g., medium or large sized dots), e.g., compared to dots of low optical density. If dots of low optical density (e.g., which corresponds to small charge in the developer roller) are used, then the output image tends to form a dusting of toner, rather than true dots. Such dusting of toner for dots of low optical density is generally acceptable when the dots are isolated (e.g., spaced sufficiently apart) in the printed image.
However, if dots (e.g., dots of low or medium optical density) are placed in close proximity in a halftone image, while printing the dots in a laser printer, these dots start to reinforce one another and create clumps. This may cause the printed image to appear grainy and of relatively poor quality.